The Secret Service has prepared for every scenario possible to keep the Republican National Convention in Cleveland safe next week, Director Joseph Clancy said Thursday, noting that he and Homeland Security Secretary Jeh Johnson will be in the city personally again on Friday to inspect the arrangements.

The deaths of police officers in Dallas and the shootings of two black men in Louisiana and Minnesota remain in the "hearts and prayers" of the Secret Service, Clancy told MSNBC's Andrea Mitchell, but the agency plans for all events the best it can.

"We look at all the possibilities that are out there, and we do that through tabletop exercises," said Clancy. "We bring all the different public safety and law enforcement entities at all levels together and we do several scenarios of what can be expected, whether it's a sniper attack or whether it's a mass attack or whether it's large protests, small protests or even medical issues. All the scenarios we can dream up we put out on the table and discuss them."

But Clancy said that he wouldn't say that extra assets have been added over the unrest over the shootings.

"We went out there and we sent our coordinators out to Cleveland and Philadelphia, approximately nine months ago, and we've developed a plan with our partners and our partners have been terrific partners throughout this planning process," said Clancy. "We've planned for every scenario so we don't have to ramp up based on what happens in the country that day."

People who plan to go to the convention should know there will be structure in the name of security, and there will be "inconveniences because there's a lot of checkpoints," said Clancy. "There's magnetometers. We do that so everyone can have a safe, secure environment to enjoy the RNC and the DNC as well."

However, Clancy said the Secret Service does respect the First Amendment rights of all, and wants to make sure everyone has a chance to be heard, whether "you're participating in the arena, Quicken Loans Arena, or whether you're out in the street. And that's why we put these structures in place."

Ohio does have an open carry law for weapons, but that will stop at the perimeter of the secure zone the Secret Service has set up at the convention site, said Clancy.

"This is not something new," he said. "As you know, the president and vice president, they travel in states where there are these open carry laws. Certainly we abide by that and respect that. And we have enough assets in place to try to accommodate those."

Also, Ohio officials and law enforcement are very well prepared, and Clancy said he has great confidence in Cleveland Police Chief Calvin Williams, who he called a "very impressive leader," and the Cleveland Police Department has gone through significant training, as has the Philadelphia police.

"We've got a model for these national special security events," said Clancy. "Cleveland will be our 53rd. Since 1998 we've been doing these. Philadelphia will be the 54th. And I think the model that we have in place really works well with the subcommittees."

The Secret Service has prepared for every scenario possible to keep the Republican National Convention in Cleveland safe next week, Director Joseph Clancy said Thursday, noting that he and Homeland Security Secretary Jeh Johnson will be in the city personally again on...